Propellant gas thrusters are used in rockets, missiles, interceptors, and various other vehicles and environments. For example, propellant gas thrusters may be used to control both vehicle propulsion, steering, lateral divert and attitude control for missiles, munitions, and various spacecraft. A propellant gas thruster typically receives high-energy propellant gas from, for example, a solid or liquid propellant gas generator. Depending upon the particular end-use system in which the propellant gas thruster is installed, propellant gas flow through the propellant gas thruster is preferably controlled to vary the thrust, pitch, yaw, roll, spin rate, and/or other dynamic characteristics of a vehicle in flight.
For some end-use systems, there is a need for a propellant gas thruster that is able to supply thrust in the range of 2 to 20 pound-force (lbf) with a small weight and electrical power allocation. It is furthermore desirable that the propellant gas thruster is sufficiently controllable to allow for propellant management, and that it exhibits a relatively fine impulse resolution (e.g., a relatively low minimum impulse bit (MIB) performance). Presently known propellant gas thruster configurations do not address this combination of needs. For example, poppet valve thrusters, due to the on-off behavior of a poppet valve, may be used to provide propellant management. However, poppet valve thrusters provide relatively high thrust levels and exhibit relatively coarse MIB performance. Another propellant gas thruster configuration uses pintle valves. Pintle valve thrusters provide a modulated output and exhibit thrust levels similar to poppet valve thrusters, but tend to have slower response times. One other known thruster configuration, which uses diverter valves, does supply thrust levels in the 2 to 20 lbf range and does exhibit favorable MIB performance. Unfortunately, because diverter valves supply a constant gas flow, diverter valve thrusters may not be used to provide propellant gas management.
Hence, there is a need for a propellant gas thruster that is able to supply thrust over a relatively wide range, from a relatively low value to a relatively high thrust value, and is sufficiently controllable to allow for propellant management, and that exhibits relatively fine MIB performance. The present invention addresses at least this need.